Process of making sodium sulphide



Patented ay ll, 119200 arser any hr, essence, on a umina, xaurucn'r.

raocnss on Maxine sonrcrr sunrnrna Etc Drawing This invention relates to the production of sodium sulphide from sodium sulphate by reduction with carbon in a reducing atmosphere, the carbon beingperferably present in excess of the theoretical amount necessary for the reaction.

Many efiorts have been made to produce sodium sulphide by direct reduction of sodium sulphate with carbon but heretofore, so

far as I am advised, no practical or commercial success has been obtained in producing sodium sulphide by any such method. 'lests which l have made of such prior proposed methods as set out in the patents and literature on the subject have produced yields of only about to 65 per cent of the theoretical yield and such yields are insufficient in commercial practice As a result of experiments which I have conducted l have found that it is possible by my improved'method to obtain commercial yields of sodium sulphide by conducting the reducing operation at difierent and successively increasing temperatures from about 050 l to about 900 F, the increase in temperature above 050 being slow and preferably consuming about 1 hour and 20 minutes or upward in the reduction of 2,000 pounds of sodium sulphate and the temperature being so regulated or controlled that fusion of the intermediate mixture of sodium sulphate and sodium sulphide is prevented, and that l am able to obtain yields of 08 per cent and upward of the theoretical yield of sodium sulphide by so regulating the temperatures at'which the reduction of the sodiuni-sulphate takes place that from approxie mately 20 tov 25 per cent of the theoretical yield or sodium sulphide is obtained at a -0.! temperature not to exceed approximately 050 (1, 40 to 60 per cent of the theoretical yield at not to exceed approximately 700 C, and the remainder ofthe yield at a temperatureiot not to exceed approximately 900 (1. i= Heretofore" it hasbeen proposed to produce sodium sulphide byheating sodium sulphate -with an excess of carbon in the form of coal to a temperature of from 700 to 800 C. In such process 'aconsiderable yield of sodium sulphide is obtained, the

retical yield of sodium sulphite is obtained. The temperature is then gradually raised to Application tiled August 20, 1025. Serial Ito. 52,030,

product of the reaction containing in addition to the sodium sulphide, unreduced sodi-v um sulphate, sodium sulphite and other undesired products. ln carrying out this process I found that the yield of sodium sulphide v frequently is as low as 20 per cent of the theoretical yield and l was unable by such method in any case to obtain yields materially in excess of 05 per cent. Furthermore thepresence of other salts in the prodcc not render it unsuitable for some of the'important uses of sodium sulphide in the chem ical industries so that such process is i" practical for commercial use both on account of lack of economy and on account of the 5 impure product obtained. i ln the'practice of my process 1 cm loy carbonaceous matter preferably in the "orm of both coal and coke in the preferred proportions of about 600800 pounds of coal to '50 about 800-000 pounds of coke and I prefer to employ approximately 1,400 pounds oi the coal and coke mixture to 2,000 pounds of the sodium sulphate.

The reduction may be advantageously car- Jc ried out in either a batch furnace such for example, as the Brookner furnace or in a rotary tube furnace of ordinary construction. in the use of both batch and rotary tube furnaces l have obtained the'best results by the use of a mixture of about 800 pounds of coal to about 600 pounds of coke in the treatment of 2,000 pounds oi sulphate, The proportion of coal to the colre is of con siderable importance in obtaining the maximum yield of sodium sulphide,

in my preferred reducing treatment the mixture or" the carbonaceous matter and sulphate is first subjected to a temperature of approximately 050 G. until from about 20 to 25 per cent of the theoretical yield ort sodium sulphide is obtained. 1 The temperature is then gradually raised to about 700 until from 40 to 00 per cent of the theoabout 900 C, until the maximum yield is obtained. l have found such maximum yield to vary from 93 per cent to, in some cases,

upward of 95 per cent ofthe theoretical yield. W0

It is important in the practice of my process that the temperature at no stage of the operation be permitted to reach a point at which the intermediate mixture of sodium sulphate and the sodium sulphide will fuse.

The temperature should not be raised to around 7 00 C. until at least 20 per cent of the theoretical yield of sodium sulphide is obtained and should not be raised to around 900 C. until at least 40 per cent of the theoretical yield is obtained.

In the reducing operation it is necessary to control the supply or" air at all times to prevent the formation of thiosuphates and carbonates due to oxidation by air.

The reducing operation requires from about an hour and twenty minutes upward.

The reduction is effected in a reducing atmosphere and the sodium sulphide produced is preferably cooled out of contact with the air.

The sodium sulphide is separated by leaching and is preferably purified by crystallization to obtain the sulphide in marketable form.

The coke from which the sodium sulphide is removed by the leaching operation is suitable for use with coal in the reduction of additional sodium sulphate.

While I have described in detail the preferred practice of my process it is to be understood that the procedure may be variously modified and that other suitable reducing apparatus than those herein referred to may be employed without departing from the spirit of my invention or the scope of the subjoined claims.

Having described my invention, 1 claim:

1. The process of producing sodium sulphide which comprises heating sodium sulphate and carbonaceous matter at a temperature of not to exceed about 650 C. until at least about 20 per cent of the theoretical yield of sodium sulphide is produced and then increasing the temperature as increasing amounts of sodium sulphide are produced, to approximately 900 C.

2. The process of'producing sodium sulphide which comprises heating sodium sulphate and carbonaceous matter to a temperature of not to exceed about 650 C. until at least 20 per cent of the theoretical yield of sodium sulphide is obtained, then gradually increasing the temperature to about 900 0., the temperature being maintained during the reducing operation below the point of :fiusion of the mixture of unreduced sodium sulphate and the reduced sodium sulphide.

3. The process of producing sodium sulphide which comprises reducing sodium sulphate to sodium sulphide by the action of carbonaceous matter at a temperature of not to exceed about 650 C. until from about 20 to 25 per cent of the theoretical yield of sodium sulphide is obtained, then increasmeets? ing the temperature to not to exceed about 700 C. until from 4:0 to 60 per cent of the theoretical yield of sodium sulphide is obtained and then gradually increasing the temperature to approximately 900 C.

4. In a process of producing sodium sulphide by the reduction of sodium sulphate by carbonaceous matter and heat, the steps of adding thereto coal and coke in the proportions of from about 6-8 parts by weight of coal to about 8-6 parts by weight of coke and subjecting the coal, coke, and sulphate mixture to gradually increasing reducing temperatures in a reducing atmosphere.

5. In a process of producing sodium sulphide from sodium sulphate, the steps of adding to sodium sulphate, coal and coke in the proportions of about 600-800 pound; of coal and 800-600 pounds of coke to about 2,000 pounds of sodium sulphate and subjecting the mixture to gradually increasing reducing temperatures in a reducing atmosphere.

6. The herein described process of producing sodium sulphide comprising mixing sodium sulphate, coal and coke in the proportions of about 600-800 pounds of coal and 800-600 ounds of coke to about 2,000 pounds 0 sodium sulphate, heating the mixture in a reducing atmosphere to a temperature of not to exceed about 650 C. until about 20 to 25 per cent of the theoretical yield of sodium sulphide is obtained, then further heating the mixture to not to exceed about 7 00 C. until from about 4.0 to 60 per cent of the theorectical yield of sodium sulphide is obtained and then gradually heating the mass to about 900 C.

7. The herein described process of producing sodium sulphide comprising mixing sodium sulphate, coal and coke in the proportions of about 600-800 pounds of coal and 800-600 pounds of coke to about 2,000 pounds of sodium sulphate, heating the mixture in a reducing atmosphere to a temperature of not to exceed about 650 C. until about 20 to 25 per cent of the theoretical yield of sodium sulphide isobtained, then further lieatin the mixture to not to exceed about 700 until from about 40 to 60 per cent of the theoretical yield of sodium sulphide is obtained, then gradually heating the mass to about 900 C., cooling the product out of contact with the air and separating the sodium sulphide from the resulting mass.

8. The process of producin sodium sulhide comprising reducing s ium sulphate in the presence of carbonaceous matter at difierent and gradually increasing temperatures, such temperatures being maintained throughout the reducing treatment at below the fusing point of the ntermediate mixture of unreduced sodium sulphate and reduced sodium sulphide.

9. The process ofproducing sodium sulphide comprising adding to sodium sulphate, the resulting mass and utilizing the residue coal and coke in the proportion of about with additional coal and sodium sulphate in 600-800 pounds of coal and 800-600 pounds the first step of the process. 10 of coke to about 2,000 pounds of sodium sul- In testimony whereof I aflix my signa 5 phate, subjecting the mixture-to increasing ture.

reduclng temperatures in a reducing atmosphere, separating the sodium sulphide from HARRY P. BASSETT. 

